Opencv3中Rect和rectangle函数

一、Rect类

template<typename _Tp> class Rect_
{
public:
    typedef _Tp value_type;

    //! various constructors
    Rect_();
    Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height);
    Rect_(const Rect_& r);
    Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz);
    Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2);

    Rect_& operator = ( const Rect_& r );
    //! the top-left corner
    Point_<_Tp> tl() const;
    //! the bottom-right corner
    Point_<_Tp> br() const;

    //! size (width, height) of the rectangle
    Size_<_Tp> size() const;
    //! area (width*height) of the rectangle
    _Tp area() const;

    //! conversion to another data type
    template<typename _Tp2> operator Rect_<_Tp2>() const;

    //! checks whether the rectangle contains the point
    bool contains(const Point_<_Tp>& pt) const;

    _Tp x, y, width, height; //< the top-left corner, as well as width and height of the rectangle
};

Rect_()，形参列表为空，即定义一个空窗口（默认值为：x=y=width=height=0）；
Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height)，定义一个左上角点坐标为(_x, _y)的_width*_height矩形窗口；（这个最常用）
Rect_(const Rect_& r)，使用其他的Rect_对象初始化；
Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz)，分别将位置坐标(_x, _y)和窗口大小(_width, _height)用Point_和Size_对象初始化；

Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2)，分别将坐标位置(_x, _y)和窗口大小(_width, _height)用Point_和Point_对象初始化。

//如果创建一个Rect对象rect(100, 50, 50, 100)，那么rect会有以下几个功能：  
rect.area();     //返回rect的面积 5000  
rect.size();     //返回rect的尺寸 [50 × 100]  
rect.tl();       //返回rect的左上顶点的坐标 [100, 50]  
rect.br();       //返回rect的右下顶点的坐标 [150, 150]  
rect.width();    //返回rect的宽度 50  
rect.height();   //返回rect的高度 100  
rect.contains(Point(x, y));  //返回布尔变量，判断rect是否包含Point(x, y)点  
  
//还可以求两个矩形的交集和并集  
rect = rect1 & rect2;  
rect = rect1 | rect2;  
  
//还可以对矩形进行平移和缩放    
rect = rect + Point(-100, 100); //平移，也就是左上顶点的x坐标-100，y坐标+100  
rect = rect + Size(-100, 100);  //缩放，左上顶点不变，宽度-100，高度+100  
  
//还可以对矩形进行对比，返回布尔变量  
rect1 == rect2;  
rect1 != rect2;  
  
//OpenCV里貌似没有判断rect1是否在rect2里面的功能，所以自己写一个吧  
bool isInside(Rect rect1, Rect rect2)  
{  
    return (rect1 == (rect1&rect2));  
}  
  
//OpenCV貌似也没有获取矩形中心点的功能，还是自己写一个  
Point getCenterPoint(Rect rect)  
{  
    Point cpt;  
    cpt.x = rect.x + cvRound(rect.width/2.0);  
    cpt.y = rect.y + cvRound(rect.height/2.0);  
    return cpt;  
}  
  
//围绕矩形中心缩放  
Rect rectCenterScale(Rect rect, Size size)  
{  
    rect = rect + size;   
    Point pt;  
    pt.x = cvRound(size.width/2.0);  
    pt.y = cvRound(size.height/2.0);  
    return (rect-pt);  
}  

二、rectangle函数

void rectangle(InputOutputArray img, Point pt1, Point pt2,
                          const Scalar& color, int thickness = 1,
                          int lineType = LINE_8, int shift = 0);

简介：使用对角线的两点pt1，pt2画一个矩形轮廓或者填充矩形

@param img Image.
@param pt1 Vertex of the rectangle.
@param pt2 Vertex of the rectangle opposite to pt1 .
@param color Rectangle color or brightness (grayscale image).color 线条颜色 (RGB) 或亮度（灰度图像 ）
@param thickness Thickness of lines that make up the rectangle. Negative values, like CV_FILLED ,
mean that the function has to draw a filled rectangle.thickness 组成矩形的线条的粗细程度。取负值时（如 CV_FILLED）函数绘制填充了色彩的矩形

@param lineType Type of the line. 

//! type of line
enum LineTypes {
    FILLED  = -1,
    LINE_4  = 4, //!< 4-connected line
    LINE_8  = 8, //!< 8-connected line
    LINE_AA = 16 //!< antialiased line
};

@param shift Number of fractional bits in the point coordinates.坐标点的小数点的位数

void rectangle(CV_IN_OUT Mat& img, Rect rec,
                          const Scalar& color, int thickness = 1,
                          int lineType = LINE_8, int shift = 0);

简介：使用矩阵类rec画一个矩形轮廓或者填充矩形

其他参数同上

三、实例示范

    rectangle(matImage,Point(20,200),Point(200,300),Scalar(255,0,0),1,1,0);  

   //Rect(int a,int b,int c,int d)a,b为矩形的左上角坐标,c,d为矩形的长和宽  

    rectangle(matImage,Rect(100,300,20,200),Scalar(0,0,255),1,1,0);  

参考链接：

https://blog.youkuaiyun.com/yhl_leo/article/details/50593825

https://blog.youkuaiyun.com/kh1445291129/article/details/51149849

https://blog.youkuaiyun.com/ubunfans/article/details/24421981